/* Generic symbol-table support for the BFD library.
   Copyright (C) 1990-2020 Free Software Foundation, Inc.
   Written by Cygnus Support.

   This file is part of BFD, the Binary File Descriptor library.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
   MA 02110-1301, USA.  */

/*
SECTION
	Symbols

	BFD tries to maintain as much symbol information as it can when
	it moves information from file to file. BFD passes information
	to applications though the <<asymbol>> structure. When the
	application requests the symbol table, BFD reads the table in
	the native form and translates parts of it into the internal
	format. To maintain more than the information passed to
	applications, some targets keep some information ``behind the
	scenes'' in a structure only the particular back end knows
	about. For example, the coff back end keeps the original
	symbol table structure as well as the canonical structure when
	a BFD is read in. On output, the coff back end can reconstruct
	the output symbol table so that no information is lost, even
	information unique to coff which BFD doesn't know or
	understand. If a coff symbol table were read, but were written
	through an a.out back end, all the coff specific information
	would be lost. The symbol table of a BFD
	is not necessarily read in until a canonicalize request is
	made. Then the BFD back end fills in a table provided by the
	application with pointers to the canonical information.  To
	output symbols, the application provides BFD with a table of
	pointers to pointers to <<asymbol>>s. This allows applications
	like the linker to output a symbol as it was read, since the ``behind
	the scenes'' information will be still available.
@menu
@* Reading Symbols::
@* Writing Symbols::
@* Mini Symbols::
@* typedef asymbol::
@* symbol handling functions::
@end menu

INODE
Reading Symbols, Writing Symbols, Symbols, Symbols
SUBSECTION
	Reading symbols

	There are two stages to reading a symbol table from a BFD:
	allocating storage, and the actual reading process. This is an
	excerpt from an application which reads the symbol table:

|         long storage_needed;
|         asymbol **symbol_table;
|         long number_of_symbols;
|         long i;
|
|         storage_needed = bfd_get_symtab_upper_bound (abfd);
|
|         if (storage_needed < 0)
|           FAIL
|
|         if (storage_needed == 0)
|           return;
|
|         symbol_table = xmalloc (storage_needed);
|           ...
|         number_of_symbols =
|            bfd_canonicalize_symtab (abfd, symbol_table);
|
|         if (number_of_symbols < 0)
|           FAIL
|
|         for (i = 0; i < number_of_symbols; i++)
|           process_symbol (symbol_table[i]);

	All storage for the symbols themselves is in an objalloc
	connected to the BFD; it is freed when the BFD is closed.

INODE
Writing Symbols, Mini Symbols, Reading Symbols, Symbols
SUBSECTION
	Writing symbols

	Writing of a symbol table is automatic when a BFD open for
	writing is closed. The application attaches a vector of
	pointers to pointers to symbols to the BFD being written, and
	fills in the symbol count. The close and cleanup code reads
	through the table provided and performs all the necessary
	operations. The BFD output code must always be provided with an
	``owned'' symbol: one which has come from another BFD, or one
	which has been created using <<bfd_make_empty_symbol>>.  Here is an
	example showing the creation of a symbol table with only one element:

|       #include "sysdep.h"
|       #include "bfd.h"
|       int main (void)
|       {
|         bfd *abfd;
|         asymbol *ptrs[2];
|         asymbol *new;
|
|         abfd = bfd_openw ("foo","a.out-sunos-big");
|         bfd_set_format (abfd, bfd_object);
|         new = bfd_make_empty_symbol (abfd);
|         new->name = "dummy_symbol";
|         new->section = bfd_make_section_old_way (abfd, ".text");
|         new->flags = BSF_GLOBAL;
|         new->value = 0x12345;
|
|         ptrs[0] = new;
|         ptrs[1] = 0;
|
|         bfd_set_symtab (abfd, ptrs, 1);
|         bfd_close (abfd);
|         return 0;
|       }
|
|       ./makesym
|       nm foo
|       00012345 A dummy_symbol

	Many formats cannot represent arbitrary symbol information; for
	instance, the <<a.out>> object format does not allow an
	arbitrary number of sections. A symbol pointing to a section
	which is not one  of <<.text>>, <<.data>> or <<.bss>> cannot
	be described.

INODE
Mini Symbols, typedef asymbol, Writing Symbols, Symbols
SUBSECTION
	Mini Symbols

	Mini symbols provide read-only access to the symbol table.
	They use less memory space, but require more time to access.
	They can be useful for tools like nm or objdump, which may
	have to handle symbol tables of extremely large executables.

	The <<bfd_read_minisymbols>> function will read the symbols
	into memory in an internal form.  It will return a <<void *>>
	pointer to a block of memory, a symbol count, and the size of
	each symbol.  The pointer is allocated using <<malloc>>, and
	should be freed by the caller when it is no longer needed.

	The function <<bfd_minisymbol_to_symbol>> will take a pointer
	to a minisymbol, and a pointer to a structure returned by
	<<bfd_make_empty_symbol>>, and return a <<asymbol>> structure.
	The return value may or may not be the same as the value from
	<<bfd_make_empty_symbol>> which was passed in.

*/

/*
DOCDD
INODE
typedef asymbol, symbol handling functions, Mini Symbols, Symbols

*/
/*
SUBSECTION
	typedef asymbol

	An <<asymbol>> has the form:

*/

/*
CODE_FRAGMENT

.
.typedef struct bfd_symbol
.{
.  {* A pointer to the BFD which owns the symbol. This information
.     is necessary so that a back end can work out what additional
.     information (invisible to the application writer) is carried
.     with the symbol.
.
.     This field is *almost* redundant, since you can use section->owner
.     instead, except that some symbols point to the global sections
.     bfd_{abs,com,und}_section.  This could be fixed by making
.     these globals be per-bfd (or per-target-flavor).  FIXME.  *}
.  struct bfd *the_bfd; {* Use bfd_asymbol_bfd(sym) to access this field.  *}
.
.  {* The text of the symbol. The name is left alone, and not copied; the
.     application may not alter it.  *}
.  const char *name;
.
.  {* The value of the symbol.  This really should be a union of a
.     numeric value with a pointer, since some flags indicate that
.     a pointer to another symbol is stored here.  *}
.  symvalue value;
.
.  {* Attributes of a symbol.  *}
.#define BSF_NO_FLAGS            0
.
.  {* The symbol has local scope; <<static>> in <<C>>. The value
.     is the offset into the section of the data.  *}
.#define BSF_LOCAL               (1 << 0)
.
.  {* The symbol has global scope; initialized data in <<C>>. The
.     value is the offset into the section of the data.  *}
.#define BSF_GLOBAL              (1 << 1)
.
.  {* The symbol has global scope and is exported. The value is
.     the offset into the section of the data.  *}
.#define BSF_EXPORT              BSF_GLOBAL {* No real difference.  *}
.
.  {* A normal C symbol would be one of:
.     <<BSF_LOCAL>>, <<BSF_UNDEFINED>> or <<BSF_GLOBAL>>.  *}
.
.  {* The symbol is a debugging record. The value has an arbitrary
.     meaning, unless BSF_DEBUGGING_RELOC is also set.  *}
.#define BSF_DEBUGGING           (1 << 2)
.
.  {* The symbol denotes a function entry point.  Used in ELF,
.     perhaps others someday.  *}
.#define BSF_FUNCTION            (1 << 3)
.
.  {* Used by the linker.  *}
.#define BSF_KEEP                (1 << 5)
.
.  {* An ELF common symbol.  *}
.#define BSF_ELF_COMMON          (1 << 6)
.
.  {* A weak global symbol, overridable without warnings by
.     a regular global symbol of the same name.  *}
.#define BSF_WEAK                (1 << 7)
.
.  {* This symbol was created to point to a section, e.g. ELF's
.     STT_SECTION symbols.  *}
.#define BSF_SECTION_SYM         (1 << 8)
.
.  {* The symbol used to be a common symbol, but now it is
.     allocated.  *}
.#define BSF_OLD_COMMON          (1 << 9)
.
.  {* In some files the type of a symbol sometimes alters its
.     location in an output file - ie in coff a <<ISFCN>> symbol
.     which is also <<C_EXT>> symbol appears where it was
.     declared and not at the end of a section.  This bit is set
.     by the target BFD part to convey this information.  *}
.#define BSF_NOT_AT_END          (1 << 10)
.
.  {* Signal that the symbol is the label of constructor section.  *}
.#define BSF_CONSTRUCTOR         (1 << 11)
.
.  {* Signal that the symbol is a warning symbol.  The name is a
.     warning.  The name of the next symbol is the one to warn about;
.     if a reference is made to a symbol with the same name as the next
.     symbol, a warning is issued by the linker.  *}
.#define BSF_WARNING             (1 << 12)
.
.  {* Signal that the symbol is indirect.  This symbol is an indirect
.     pointer to the symbol with the same name as the next symbol.  *}
.#define BSF_INDIRECT            (1 << 13)
.
.  {* BSF_FILE marks symbols that contain a file name.  This is used
.     for ELF STT_FILE symbols.  *}
.#define BSF_FILE                (1 << 14)
.
.  {* Symbol is from dynamic linking information.  *}
.#define BSF_DYNAMIC             (1 << 15)
.
.  {* The symbol denotes a data object.  Used in ELF, and perhaps
.     others someday.  *}
.#define BSF_OBJECT              (1 << 16)
.
.  {* This symbol is a debugging symbol.  The value is the offset
.     into the section of the data.  BSF_DEBUGGING should be set
.     as well.  *}
.#define BSF_DEBUGGING_RELOC     (1 << 17)
.
.  {* This symbol is thread local.  Used in ELF.  *}
.#define BSF_THREAD_LOCAL        (1 << 18)
.
.  {* This symbol represents a complex relocation expression,
.     with the expression tree serialized in the symbol name.  *}
.#define BSF_RELC                (1 << 19)
.
.  {* This symbol represents a signed complex relocation expression,
.     with the expression tree serialized in the symbol name.  *}
.#define BSF_SRELC               (1 << 20)
.
.  {* This symbol was created by bfd_get_synthetic_symtab.  *}
.#define BSF_SYNTHETIC           (1 << 21)
.
.  {* This symbol is an indirect code object.  Unrelated to BSF_INDIRECT.
.     The dynamic linker will compute the value of this symbol by
.     calling the function that it points to.  BSF_FUNCTION must
.     also be also set.  *}
.#define BSF_GNU_INDIRECT_FUNCTION (1 << 22)
.  {* This symbol is a globally unique data object.  The dynamic linker
.     will make sure that in the entire process there is just one symbol
.     with this name and type in use.  BSF_OBJECT must also be set.  *}
.#define BSF_GNU_UNIQUE          (1 << 23)
.
.  flagword flags;
.
.  {* A pointer to the section to which this symbol is
.     relative.  This will always be non NULL, there are special
.     sections for undefined and absolute symbols.  *}
.  struct bfd_section *section;
.
.  {* Back end special data.  *}
.  union
.    {
.      void *p;
.      bfd_vma i;
.    }
.  udata;
.}
.asymbol;
.
*/

#include "sysdep.h"
#include "bfd.h"
#include "libbfd.h"
#include "safe-ctype.h"
#include "bfdlink.h"
#include "aout/stab_gnu.h"

/*
DOCDD
INODE
symbol handling functions,  , typedef asymbol, Symbols
SUBSECTION
	Symbol handling functions
*/

/*
FUNCTION
	bfd_get_symtab_upper_bound

DESCRIPTION
	Return the number of bytes required to store a vector of pointers
	to <<asymbols>> for all the symbols in the BFD @var{abfd},
	including a terminal NULL pointer. If there are no symbols in
	the BFD, then return 0.  If an error occurs, return -1.

.#define bfd_get_symtab_upper_bound(abfd) \
.	BFD_SEND (abfd, _bfd_get_symtab_upper_bound, (abfd))
.
*/

/*
FUNCTION
	bfd_is_local_label

SYNOPSIS
	bfd_boolean bfd_is_local_label (bfd *abfd, asymbol *sym);

DESCRIPTION
	Return TRUE if the given symbol @var{sym} in the BFD @var{abfd} is
	a compiler generated local label, else return FALSE.
*/

/*
FUNCTION
	bfd_is_local_label_name

SYNOPSIS
	bfd_boolean bfd_is_local_label_name (bfd *abfd, const char *name);

DESCRIPTION
	Return TRUE if a symbol with the name @var{name} in the BFD
	@var{abfd} is a compiler generated local label, else return
	FALSE.  This just checks whether the name has the form of a
	local label.

.#define bfd_is_local_label_name(abfd, name) \
.	BFD_SEND (abfd, _bfd_is_local_label_name, (abfd, name))
.
*/

/*
FUNCTION
	bfd_is_target_special_symbol

SYNOPSIS
	bfd_boolean bfd_is_target_special_symbol (bfd *abfd, asymbol *sym);

DESCRIPTION
	Return TRUE iff a symbol @var{sym} in the BFD @var{abfd} is something
	special to the particular target represented by the BFD.  Such symbols
	should normally not be mentioned to the user.

.#define bfd_is_target_special_symbol(abfd, sym) \
.	BFD_SEND (abfd, _bfd_is_target_special_symbol, (abfd, sym))
.
*/

/*
FUNCTION
	bfd_canonicalize_symtab

DESCRIPTION
	Read the symbols from the BFD @var{abfd}, and fills in
	the vector @var{location} with pointers to the symbols and
	a trailing NULL.
	Return the actual number of symbol pointers, not
	including the NULL.

.#define bfd_canonicalize_symtab(abfd, location) \
.	BFD_SEND (abfd, _bfd_canonicalize_symtab, (abfd, location))
.
*/

/*
FUNCTION
	bfd_set_symtab

SYNOPSIS
	bfd_boolean bfd_set_symtab
	  (bfd *abfd, asymbol **location, unsigned int count);

DESCRIPTION
	Arrange that when the output BFD @var{abfd} is closed,
	the table @var{location} of @var{count} pointers to symbols
	will be written.
*/

/*
FUNCTION
	bfd_print_symbol_vandf

SYNOPSIS
	void bfd_print_symbol_vandf (bfd *abfd, void *file, asymbol *symbol);

DESCRIPTION
	Print the value and flags of the @var{symbol} supplied to the
	stream @var{file}.
*/

/*
FUNCTION
	bfd_make_empty_symbol

DESCRIPTION
	Create a new <<asymbol>> structure for the BFD @var{abfd}
	and return a pointer to it.

	This routine is necessary because each back end has private
	information surrounding the <<asymbol>>. Building your own
	<<asymbol>> and pointing to it will not create the private
	information, and will cause problems later on.

.#define bfd_make_empty_symbol(abfd) \
.	BFD_SEND (abfd, _bfd_make_empty_symbol, (abfd))
.
*/

/*
FUNCTION
	_bfd_generic_make_empty_symbol

SYNOPSIS
	asymbol *_bfd_generic_make_empty_symbol (bfd *);

DESCRIPTION
	Create a new <<asymbol>> structure for the BFD @var{abfd}
	and return a pointer to it.  Used by core file routines,
	binary back-end and anywhere else where no private info
	is needed.
*/

/*
FUNCTION
	bfd_make_debug_symbol

DESCRIPTION
	Create a new <<asymbol>> structure for the BFD @var{abfd},
	to be used as a debugging symbol.  Further details of its use have
	yet to be worked out.

.#define bfd_make_debug_symbol(abfd,ptr,size) \
.	BFD_SEND (abfd, _bfd_make_debug_symbol, (abfd, ptr, size))
.
*/

/* Return the single-character symbol type corresponding to
   section S, or '?' for an unknown COFF section.

   Check for leading strings which match, followed by a number, '.',
   or '$' so .text5 matches the .text entry, but .init_array doesn't
   match the .init entry.  */

/* Return the single-character symbol type corresponding to section
   SECTION, or '?' for an unknown section.  This uses section flags to
   identify sections.

   FIXME These types are unhandled: c, i, e, p.  If we handled these also,
   we could perhaps obsolete coff_section_type.  */

/*
FUNCTION
	bfd_decode_symclass

DESCRIPTION
	Return a character corresponding to the symbol
	class of @var{symbol}, or '?' for an unknown class.

SYNOPSIS
	int bfd_decode_symclass (asymbol *symbol);
*/

/*
FUNCTION
	bfd_is_undefined_symclass

DESCRIPTION
	Returns non-zero if the class symbol returned by
	bfd_decode_symclass represents an undefined symbol.
	Returns zero otherwise.

SYNOPSIS
	bfd_boolean bfd_is_undefined_symclass (int symclass);
*/

/*
FUNCTION
	bfd_symbol_info

DESCRIPTION
	Fill in the basic info about symbol that nm needs.
	Additional info may be added by the back-ends after
	calling this function.

SYNOPSIS
	void bfd_symbol_info (asymbol *symbol, symbol_info *ret);
*/

/*
FUNCTION
	bfd_copy_private_symbol_data

SYNOPSIS
	bfd_boolean bfd_copy_private_symbol_data
	  (bfd *ibfd, asymbol *isym, bfd *obfd, asymbol *osym);

DESCRIPTION
	Copy private symbol information from @var{isym} in the BFD
	@var{ibfd} to the symbol @var{osym} in the BFD @var{obfd}.
	Return <<TRUE>> on success, <<FALSE>> on error.  Possible error
	returns are:

	o <<bfd_error_no_memory>> -
	Not enough memory exists to create private data for @var{osec}.

.#define bfd_copy_private_symbol_data(ibfd, isymbol, obfd, osymbol) \
.	BFD_SEND (obfd, _bfd_copy_private_symbol_data, \
.		  (ibfd, isymbol, obfd, osymbol))
.
*/

/* The generic version of the function which returns mini symbols.
   This is used when the backend does not provide a more efficient
   version.  It just uses BFD asymbol structures as mini symbols.  */
